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| 1 | +// +build !go1.11 |
| 2 | +// file for compatibility with go versions prior to 1.11 |
| 3 | + |
| 4 | +package csrf |
| 5 | + |
| 6 | +import ( |
| 7 | + "net/http" |
| 8 | + "time" |
| 9 | + |
| 10 | + "github.com/gorilla/securecookie" |
| 11 | +) |
| 12 | + |
| 13 | +// store represents the session storage used for CSRF tokens. |
| 14 | +type store interface { |
| 15 | + // Get returns the real CSRF token from the store. |
| 16 | + Get(*http.Request) ([]byte, error) |
| 17 | + // Save stores the real CSRF token in the store and writes a |
| 18 | + // cookie to the http.ResponseWriter. |
| 19 | + // For non-cookie stores, the cookie should contain a unique (256 bit) ID |
| 20 | + // or key that references the token in the backend store. |
| 21 | + // csrf.GenerateRandomBytes is a helper function for generating secure IDs. |
| 22 | + Save(token []byte, w http.ResponseWriter) error |
| 23 | +} |
| 24 | + |
| 25 | +// cookieStore is a signed cookie session store for CSRF tokens. |
| 26 | +type cookieStore struct { |
| 27 | + name string |
| 28 | + maxAge int |
| 29 | + secure bool |
| 30 | + httpOnly bool |
| 31 | + path string |
| 32 | + domain string |
| 33 | + sc *securecookie.SecureCookie |
| 34 | + sameSite SameSiteMode |
| 35 | +} |
| 36 | + |
| 37 | +// Get retrieves a CSRF token from the session cookie. It returns an empty token |
| 38 | +// if decoding fails (e.g. HMAC validation fails or the named cookie doesn't exist). |
| 39 | +func (cs *cookieStore) Get(r *http.Request) ([]byte, error) { |
| 40 | + // Retrieve the cookie from the request |
| 41 | + cookie, err := r.Cookie(cs.name) |
| 42 | + if err != nil { |
| 43 | + return nil, err |
| 44 | + } |
| 45 | + |
| 46 | + token := make([]byte, tokenLength) |
| 47 | + // Decode the HMAC authenticated cookie. |
| 48 | + err = cs.sc.Decode(cs.name, cookie.Value, &token) |
| 49 | + if err != nil { |
| 50 | + return nil, err |
| 51 | + } |
| 52 | + |
| 53 | + return token, nil |
| 54 | +} |
| 55 | + |
| 56 | +// Save stores the CSRF token in the session cookie. |
| 57 | +func (cs *cookieStore) Save(token []byte, w http.ResponseWriter) error { |
| 58 | + // Generate an encoded cookie value with the CSRF token. |
| 59 | + encoded, err := cs.sc.Encode(cs.name, token) |
| 60 | + if err != nil { |
| 61 | + return err |
| 62 | + } |
| 63 | + |
| 64 | + cookie := &http.Cookie{ |
| 65 | + Name: cs.name, |
| 66 | + Value: encoded, |
| 67 | + MaxAge: cs.maxAge, |
| 68 | + HttpOnly: cs.httpOnly, |
| 69 | + Secure: cs.secure, |
| 70 | + Path: cs.path, |
| 71 | + Domain: cs.domain, |
| 72 | + } |
| 73 | + |
| 74 | + // Set the Expires field on the cookie based on the MaxAge |
| 75 | + // If MaxAge <= 0, we don't set the Expires attribute, making the cookie |
| 76 | + // session-only. |
| 77 | + if cs.maxAge > 0 { |
| 78 | + cookie.Expires = time.Now().Add( |
| 79 | + time.Duration(cs.maxAge) * time.Second) |
| 80 | + } |
| 81 | + |
| 82 | + // Write the authenticated cookie to the response. |
| 83 | + http.SetCookie(w, cookie) |
| 84 | + |
| 85 | + return nil |
| 86 | +} |
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